Two zone pumping



Oct. 27, 1959 F, MQRGAN TWO ZONE PUMPING Filed Dec. 31, 1956 1NVENTO12.F/G- '2 nc. MORGAN BY -WLSN a Arm/vers TWO ZONE PUMPING Forrest C.Morgan, Hobbs, N. Mex., assignor to Phillips Petroleum Company, acorporation of Delaware Application December 31, 1956, Serial No.631,809 Claims. (Cl. 10S- 4) This invention relates to dual-zone pumpingapparatus. More particularly, this invention relates to a dual-Zonepumping apparatus, of the sucker rod type, for simultaneously producingoil and gas from two formations or zones within a single well borewithout commingling the oil and gas from either formation.

Wells often intersect several independent strata or formations fromwhich oil and gas may be produced. In pumping wells of this nature afterthe reservoir pressure has decreased to a point where the wells do noteffectively ow by themselves, it is often desirable or necessary thatthe oil and gas produced from the separate zones be removed asindependent streams and without commingling the same. This can beaccomplished either by employing a plurality of pumps in different wellbores in the same field or by separating the inlets of the plurality ofpumps in a single well bore in such a manner that the oil and gas in thetwo zones are removed through separate conduits. Various types ofdual-Zone deep well pump assemblies are known in the art for pumpingsuch wells, such as hydraulic pumping systems or pumping systems of thesucker rod type; the present invention is concerned with the latter typeof pumping system. Dualzone pumping systems have not been too popular,however, because they lack satisfactory means for efficiently pumpingthe two zones without commingling the oil and gas from either zone. Thepump efficiencies of these prior art pumping assemblies are often lowdue to insufficient or no separation of gas ahead of the pump-s, thusforcing the pumps to handle large quantities of gas. Low pumpefliciencies are also due to insufficient submergence of the pump, thusresulting in gas separating in the pump suction with consequent gaslocking.

Accordingly, an object of this invention is to provide an improveddualazone pumping apparatus.

Another object is to provide a dual-zone pumping apparatus, of thesucker rod type, for simultaneously producing oil and gas from twoformations or zones within a single well bore without comminglingthe oiland gas from either formation.

A further object is to provide a novel dual-zone pumping apparatuscharacterized by its desirable pumping eiciency and the absence of gaslocking.

Further objects and advantages of this invention will become apparent,to those skilled in the att, from the following discussion, appendedclaims and accompanying drawing in which:

Figure l is a schematic elevation view, shown ypartly in section, of adual-zone producing well khaving oneembodiment of the pumping apparatusof this invention inserted therein; and

2,910,002 Patented Oct. 27, 1959 ice Figure 2 is a schematic elevationview, shown partly in section, of a dual-Zone producing well havinganother embodiment of the pumping apparatus of this invention insertedtherein.

Referring to the drawing, and particularly to the well productionapparatus illustrated in Figure l, reference number 10 generallydesignates a wellV bore which extends downwardly through upperproducingv formation or zone 11 and lower producing formation'or zone12. The well bore 10 is provided with a string of casing 13 and twostrings of oil flow tubing 14, 16. Casing 13 is perforated at 17, 18 ormay have other suitable means for permitting communication of theproducing `Zones 11, 12 with the interior of the casing 13. The'annularspace between the casing 13 and tubing 14 is divided into separate lowerand upper annular fluid accumulating regions or spaces 21, 2,2,respectively, by a conventional well packer 23 at a point between thetwo producing zones A11, 12 so as to seal oif the two zones from eachother.

The lower end of oil flow tubing 14 passes through'v an opening inpacker 23 and extends therebelow a suflicient distance so that inlet 20is completely submerged in the oil accumulating in lower region 21,. Theupper end of ow tubing 14 passes through the casing head 24 and isconnected to a pipe 25 which conducts the oil produced from the lowerzone l2 to storage. A solid sucker rod 26 passes downwardly through astuing box 27 into the interior of ow tubing 14 and is mounted forreciprocation therein. Sucker rod 26 can be mounted Vfor reciprocationat the surface of the well bore by a ysuitable conventional pumpingapparatus, for example, a walking beam pumping unit. Solid sucker rod 26carries lat its lower end a hollow sucker rod 28, the upper end of whichis provided with perforations 29. The interior of ow tubing 14 isdivided by a fluid seal 33 (made of rubber, asbestos, metal, flax,Teflon, or the like) into separate lower and upper annular spaces V31,32 respectively; uid seal 33 is positioned at a point above well packer23 and below perforations 29.

The hollow sucker rod 2S, whichrpasses upwardly through an opening influid seal 33, communicates at its lower end with lower producing zone12 through a reciprocal pumping unit disposed in the lower portion offlow tubing 14, which pumping unit is adapted to i11- duce ow from lowerproducing Zone 12. The lower end of hollow sucker rod 28 carries aplunger member 34 which has an enlarged ydiameter so as to closely tit atubing section 36 which functions asa pumping cylinder. The plungermember 34 is equipped with a traveling valve which may comprise a ball37 operable with seat 28. The lower end of the flow tubing 14 isequipped with la standing valve which similarly may comprise a ball 39operable with seat 41. These two valves are adapted to permit upward owonly via the liow passage defined by hollow sucker rod 28 .and upperannular space `32. The lower end of ow tubing 14 is substantially belowthe oil-gas interface 42 and is completely submergedv in substantiallygas-free oil.

That portion ofl-ow tubing 14 immediately below packer 23 is provided`with an'inletor perforation /43 to permit communication of the lowerannular space 31 of flow tubing 14 with the gas produced from lower zone12 and presentwithin the annular casing space 21 below packer 23. Thatportion of flow tubing 14 above packer 23 and below fluid seal 33communicates with gas auxiliary flow tubing 44 (through cross-over 45)which is disposed within the annular casing space 22; the upper end ofauxiliary ow tubing 44 extends through the casing head 24 and provides aflow passage to conduct the gas produced from the lower zone 12 tostorage.

The foregoing described apparatus is employed to independently andsimultaneously produce the oil and gas from the lower producing zone 12without commingling the two streams.V The following will describe theapparatus employed to independently and simultaneously produce the oiland gas from the upper producing zone 11 without commingling the two,reference being made again to Figure l.

Oil ow tubing 16 extends downwardly within the interior of casing 13 toa point below the oil-gas interface 51 and above packer 23. The upperend of ow tubing 16 passes through casing head 24 .and is connected to apipe 52 for conducting the oil produced from the upper producing zone 11to storage. A solid sucker rod 53 passes through a suitable stuffing box54 into the interior of ow tubing 16. The lower end of solid sucker rod53 communicates with the oil in the casing 13 above packer 23 through areciprocal pumping unit disposed in the lower portion of flow tubing 16,which pumping unit induces ow from the upper producing zone 11; thestructural elements of this pumping unit are similar to that provided atthe lower end of flow tubing 14 and have been designated with primedcorresponding reference numerals. The upper end of plunger member 34' isprovided with suitable passages 56. permitting communication between thelower end of ow tubing 16 through the inlet 20' and the annular space 57above the plunger member 34', space 57 serving as a ow passage. Theupper end of casing 13 is connected to pipe 58 to conduct the gasproduced from the upper zone 11 to storage, the upper portion of casing13 serving as a ow passage for this gas.

The embodiment of my invention thus far described is particularlyapplicable where the size of the casing is relatively large, e.g., 7inches O D.. so as to accommodate the two separate oil ilow tubings 14,16 and the auxiliary flow tubing 44.

Another embodiment of my invention particularly applicable where thecasing is relatively small, e.g., 4-51/2 inches O.D., will now bedescribed, reference being made to Figure 2 in which structural elementssimilar to those of Figure 1 have been designated with primedcorresponding reference numerals.

Oil flow tubing 61 extends downwardly within casing 13 to a point belowpacker 23', the distance being such that the inlet 65 is completelysubmerged in substantially gas-free oil. Disposed within the lowerportion of flow tubing 61 is a reciprocal pumping unit similar to thatdisposed in the lower portion of the ow tubing 14 of Figure l, plungermember 62 being provided with a traveling valve having ball 63 operablewith seat 64, and the standin g valve at the end of the flow tubing 61being provided with ball 66 operable with seat 67. Plunger member 62 1sclosely tted within pumping cylinder 68 which may extend upwardly withinow tubing 61, as shown, to a pomt above packer 23'. Plunger member 62 ismounted tor reclprocation within pumping cylinder 68, reciprocat- 1ngmotion being transmitted to the plunger member 62 by hollow sucker rod28', the latter passing upwardly through fluid seal 33 into upperannular space 32'. The hollow sucker rod 28' communicates at its lowerend with lower producing zone 12 through inlet 65, and communicates atits upper end through perforations 29' with upper annular space 32. Thehollow sucker rod 28' iS carried by solid sucker rod extension 69, thelower end of which is connected to hollow sucker rod 28' at a pointwithin upper annular space 32'; solid Sucker @Xbnsion 69 passes upwardlythrough a uid seal 72.

That portion of ow tubing 61 immediately below packer 23', and theadjacent portion of pumping cylinder 68, is provided with perforations73 to permit communication of the lower annular space 31 of flow tubing61 with the gas produced from the lower producing zone 12 andaccumulating in the annular space 21 below packer 23. The portion of thelower annular space 31' above packer 23 communicates with gas auxiliaryflow tubing 44' (through cross-over 45'). The upper annular space 32 offlow tubing 61 communicates with oil ow tubing 74 (through cross-over75) which extends upwardly through the annular casing space 22 to thesurface to conduct oil produced from the lower producing zone 12 tostorage.

The reciprocal pumping unit adapted to induce the flow of upperproducing zone 11' of Figure 2 will now be described. Solid sucker rodextension 69 extends upwardly through fluid seal 72 and through astanding valve, comprising balls 76 operable with seat 77, into lowerannular space 78. The upper end of solid sucker rod extension 69 isconnected to plunger member 79 and is reciprocately carried thereby.Plunger member 79 is associated with a traveling valve, comprising ball81 operable with seat 82, which is reciprocately moved within the upperportion of pumping cylinder 83 by reason of solid sucker rod 84 which isconnected to and carries plunger member 79. Solid sucker rod 84 extendsupwardly through upper annular space 86 to the surface where it ismounted for reciprocation by the usual surface pumping apparatus, forexample, a walking beam pumping unit.

That portion of the flow tubing 61 which carries the reciprocal pumpingunit that is adapted to induce the ow of the upper producing Zone 11 isprovided with perforations 87 which are positioned at a point below theoilgas interface 51 and above uid seal 72. As such, communication 0f thelower annular space 78 with the oil in the annular casing space 22 abovepacker 23 is permitted.

The gas produced from the upper producing zone 11' rises upwardly in anannular casing space 22 to the surface where it is conducted by pipe 58to storage.

The operation of that embodiment of my novel dualzone pumping apparatusillustrated in Figure l will now be described. After the reservoirpressure is suiicient to sustain natural flow from producing formations11, 12, the apparatus of Figure l is lowered into the well bore 10. Thesurface pumping apparatus, for example. a walking beam pumping unit, isstarted and causes the reciprocation of the solid sucker rods 26, 53.The production of the lower producing zone 12 will be the initiallydescribed. The reciprocating motion of solid sucker rod 26 istransmitted to hollow sucker rod 28 which is turn actuates the plungermember 34 and its associated traveling valve. On the downstroke of theplunger member 34, ball 37 is lifted oftf its seat 38 and any oilpresent therebelow within the pumping unit is caused to ow upwardlythrough hollow sucker rod 23 into the upper annular space 32 above tluidseal 33. Upon the upstroke of plunger member 34 the ball 39 cf thestanding valve is lifted off its seat 41 and the resulting suctioncauses oil to tlow from the lower accumulating region 21 into thepumping unit from which it is produced upon the next downsrtoke of theplunger member 34. The oil produced from the lower producing zone 12 owsto the surface through the ow tubing 14 and is separate from the gasproduced from the same zone and separate from the gas and oil producedfrom the upper zone 11. The gas from the lower producing zone 12accumulates above the oil-gas interface 42 and flows under its ownpressure through perforations 43 into the lower annular space 31 in owtubing 14 from which it is produced via cross-over 45 and gas auxiliaryow tubing 44. As such, the gas produced from the lower producingformation 12 is not commingled with oil from either the lower pr upperproducing zones 11, 12.

gamona rFhe reeiprocation of solid sucker rod 53 actuates the reciprocalpumping unit in the lower portion of flow tubing 16 whereby the oilaccumulating in the upper casing space 22v is produced in a mannersimilar to the production of the oil in the lower annular casing space21. Upon the downstroke of plunger member 34', ball 37 is lifted off itsseat 38' and oil within the pumping cylinder 36 is caused to flowupwardly through the openings 56` in the plunger member 34 into the flowtubing 16 thereabove. The gas from the upper producing zone 11accumulates above the oil-gas interface 5l and iiows under its ownpressure upwardly within the annular casing space 22 to ther surface.

The operation of the dual-zone pumping apparatus illustrated in Figure 2will now be described. After the natural liow of producing zones 11, 12ceases, the apparatusl of Figure 2 is lowered in the well bore 10. Uponthe starting of suitable surface pumping apparatus, the solid sucker rod84 is caused to reciprocate, reciprocating motion being transmitted fromthe latter to the plunger member 79 and its associated traveling valve.Thek reciprocation of the plunger member 79 on its downstroke causesball 31 to be lifted from its seat 82 whereby any oil accumulating inthis reciprocal pump unit is caused to flow upwardly through theopenings 56 in the plunger member 79 and thence through the openings 85in the top of the pumping cylinder 83 into the upper annular space 86 offlow tubing 6l. Upon the upstroke `of plunger member '79 the resultingsuction causes balls v76 to be lifted from their seat 77 causing any oilaccumulating in the upper annular casing space 22 to flow through inlet87 into the reciprocal pump unit from which it is subsequently producedupon the next downstroke kof plunger member 79. Like the apparatus inFigure 1, any gas from the upper producing zone 11 which accumulatesabove the oil-gas interface 51 will flow under its own pressure upwardlythrough the casing to the surface.

Since plunger member 79 is connected to and carries .solid sucker rodextension 69, reciprocation of the former is transmitted to the latter.Consequently, the plunger .member 62 is actuated so as to cause thelower reciprocal pump means to induce the ow from the lower producingzone 12 in a manner similar to that described in regard to the operationof the apparatus of Figure l. vThat is, the oil from the lower producingzone 12 is produced independently'of the gas from the lower producing.zone 12' and independently and yseparately from the oil and gasproduced from the upper producing zone 11.

The efficient operation of the pumping apparatus of either Figure l orFigure 2 is not dependent upon the presence of anl oil-gas interface inthe casing below the well packer. The drawing illustrates an idealsituation where there is a phase separation of oil and gas below thewell packer. Although such an ideal situation is referred, itis readilyapparent that the absence of an oil-gas interface beneath the wellpacker will not prevent the gas from the lower producing zone from beingseparately produced because such an oil-gas interface will be present inthe auxiliary gas flow tubing due to the pressure differential.'Moreoven the pumping apparatus can be inserted in the well in such amanner that the oil inlets of the respective upper and lower reciprocalpump units are submerged in the oil accumulating above and below thewell packer. Although the drawing also illustrates the ideal andpreferred situation where the upper and lower reciprocal pump units arepositioned below the corresponding producing Zones, the eiciencies ofthe reciprocal pump units will not be unduly hampered if the reciprocalpump units are positioned above or adjacent their respective producingzones, as long as their respective oil inlets are submerged in theaccumulated oil.

Various modifications and alterations of my invention will becomeapparent, to those skilled in the art, from nthe foregoing discussionand accompanying drawing which 5 merely represents the preferredembodiments of my in vention, and. it is to be understood that myinvention is not tobe unduly limited thereto.

Having. described' my invention, I claim:

l. In a well bore communicating with lower and upper oil and gasproducing zones, a mechanism for simultaneously and separately producingthe oil and gas from each of said zones, comprising, in combination, acasing, liow tubing depending within said easing and annularly spacedtherefrom, a well packer within said casing between said zones andsurrounding saidY flow tubing for sealing said zones from each other andproviding lower and upper fluid accumulating regions within said casing,said lower and upper regions communicating with said lower and upperzones respectively, a first inlet in said flow tubing immediately belowsaid well packer, first reciprocal pump means in that portion of saidflow tubing depending in said lower region beneath said well packer,said first pump means having a second inlet, said first pump meanshaving a first standing valve and a first traveling valve controllingflow through said second inlet, said first traveling valve operativelycarried by a hollow rod section which slidably extends through sealingmeans in said flow tubing above said first inlet, the interior of saidhollow rod section communicating at one end with said second inletthrough said first standing valve and at the other end with a passagefor separately conducting the oil from said lower zone, a separate flowpassage communicating with said first inlet for separately conductingthe gas from said lower zone, said last-mentioned separate flow passagedefined by an auxiliary fiow tubing which depends within said upperregion and communicates with said first inlet through a cross-over atits lower end, said cross-over being connected, to said first tubing andcommunicating therewith at a point beneath said sealing means, the upperend of said auxiliary flow tubing extending to the surface of said wellbore, second reciprocal pump means disposed in said upper region saidsecond pump means having a third inlet, a second standing valve, andasecond traveling valve controlling flow through said third inlet, saidsecond travelingl valve operatively carried by a solid rod section, aseparate iiow passage communicating with said third inlet through saidvsecond standing valve for separately conducting the oil from said upperzone, the annular space above the accumulated oil in saidl upper regionfunctioning as a separate flow passage for conducting the gas from saidupper zone, and reciprocating means associated with said hollow andsolidrodsections so as to transmit reciprocating motions to said firstand second reciprocal pump means whereby flow is induced. from saidlower and upper producing zones respectively.

2. In a well bore communicating with lower and upper oil and gasproducing zones, a mechanism for simultaneously and separately producingthe oil and gas from each of said zones, comprising, in combination, acasing, a first flow tubing depending within said casing and annularlyspaced therefrom, a well packer within said casing between said zonesand surrounding said first flow tubing for sealing said zones from eachother and providing lower and upper fluid accumulating regions withinsaid casing, said lower and upper regions communicatingl with said lowerand upper zones respectively, first reciprocal pump means carried bythat portion of said first flow tubing depending in. said. lower regionAbeneath said well packer, a first inlet in said first ow tubingimmediately below said pacl-ier,-saidV first pump means having` a secondinlet, said first pump means having a first standing valve and a firsttraveling valve operatively carried by a hollow rod section whichslidably extends through a fluid seal in said first fiowtubingpositioned above said first inlet, the interior of said hollow rodsection communicating at one end with said second inlet through saidfirst standing valve and` at the other end with the interior of saidfirstflow tubing above said fiuid seal, a separate ow passagecommunicating with said first inlet for con ducting gas from said lowerregion, said last-mentioned separate flow passage defined by anauxiliary ow tubing which dependswithin said upper region andcommunicates with said first inlet through a cross-over at its lowerend, said cross-over being connected to said first tubing andcommunicating therewith at ya point beneath said sealing means, theupper end of said auxiliary flow tubing extending to the surface of saidwell bore, a second flow tubing. depending within said casing above saidpacker in said upper region, second reciprocal pump means carried by thelower portion of said second flow tubing, said second pump means having`a third inlet, a second standing valve, `and a second traveling valvecontrolling fiow through said third inlet, said second traveling valveoperatively carried by a solid rod section, a ow passage communicatingwith said third inlet through said second standing valve for separatelyconducting the oil from said upper producing zone, and reciprocatingmeans for actuating said first and second pump means.

3. In a well bore communicating with lower and upper oil and gasproducing zones, a mechanism for simultaneously and separately producingthe oil and gas from each of said zones, comprising, in combination, acasing, a first flow tubing depending within said casing and annularlyspaced therefrom, a well packer within said casing between said zonesand surrounding said first flow tubing for sealing ofi said zones fromeach other and providing lower and upper fiuid accumulating regionswithin said casing, said lower and upper regions communicating throughports in said casing with said lower and upper zones respectively, afirst inlet in said first fiow tubing immediately below said packer,first reciprocal pump means carried by that portion of said first fiowtubing depending in said lower region beneath said well packer, saidfirst pump means having a second inlet, said first pump means having afirst standing valve and a second traveling valve controlling flowthrough said second inlet, said first traveling valve operativelycarried by a hollow rod section which slidably extends upwardly througha fluid seal positioned in said first fiow tubing above said firstinlet, the interior of said hollow'rod section communicating at one endthrough said first standing valve with said second inlet and at theother end with the interior of said first fiow tubing above said fiuidseal, said hollow sucker rod section carried at its upper end by a solidsucker rod section, an auxiliary ow tubing depending within said upperregion of said casing and communicating through a cross-over with saidfirst inlet through 'an outlet in said fiow tubing positioned below saidfiuid seal, the upper end of said auxiliary fiow tubing extending to thesurface of said well bore, a second fow tubing depending within saidcasing above said packer, second reciprocal pump means carried by `thelower portion of said second flow tubing, said second pump means havinga third inlet, said second pump means having a second standing valve anda second traveling valve for controlling the fiow through said thirdinlet, said third inlet communicating through said second traveling andstanding valves with a flow passage in said second flow tubing abovesaid second pump means, said second traveling valve carried by a solidsucker rod section, the upper annulus of said casing functioning as a owpassage for the gas produced from said upper zone.

4. In a well bore communicating with lower and upper oil and gasproducing zones, a mechanism for simultaneously and separately producingthe oil and gas from each of said zones, comprising, in combination, acasing, a flow tubing depending within said casing and annularly spacedtherefrom, a well packer within said casing between said zones andsurrounding said flow tubing for sealing said zones from each other andproviding lower and upper duid accumulating regions within said casing,said lower and upper regions communicating with said lower and upperzones respectively, first reciprocal pump means carried by that portionof said ow tubing depending in said lower region beneath said wellpacker, a first inlet in said fiow tubing immediately below said packer,said first pump means having a second inlet, said first pump meanshavinga first standing valve and a first traveling valve for controlling flowthrough said second inlet, said first traveling valve operativelycarried by a hollow rod section which slidably extends through a firstfluid seal in said flow tubing positioned above said first inlet, theinterior of said hollow rod section communicating at one end with saidsecond inlet through said first standing valve and at the other end withthe interior region of said fiow tubing above said first fluid seal, aseparate ow passage communicating with said interior region forconducting oil from said lower region, a separate flow passagecommunicating with said first inlet for conducting gas from said lowerregion, said last-mentioned separate fiow passage dened by an auxiliaryflow tubing which depends within said upper region and communicates withsaid first inlet through a cross-over at its lower end, said cross-overbeing connected to said first tubing and communicating therewith at apoint beneath said sealing means, the upper end of said auxiliary flowtubing extending to the surface of said well bore, a solid rod extensionconnected to and carrying said hollow rod section which slidably extendsthrough a second fluid seal in said flow tubing which defines the upperend of said interior region, second reciprocal pump means carried bythat portion of said ow tubing above said second tiuid seal, said secondpump means having a third inlet positioned above said second fiuid seal,said second pump means having a second standing valve and a secondtraveling valve controlling flow through said third inlet, said standingvalve connected to and carrying said solid rod extension, said secondtraveling valve connected to and carried by a solid suckerV rod whichextends upwardly in said flow tubing, and a fiow passage communicatingwith said third inlet through said second standing valve for separatelyconducting the oil from said upper producing zone.

5. In a well bore communicating with lower and upper oil and gasproducing zones, a mechanism for simultaneously and separately producingthe oil and gas from each of said zones, comprising, in combination, acasing, a flow tubing depending within said casing and annularly spacedtherefrom, a well packer within said casing between said zones andsurrounding said fiow tubing for sealing said zones from each other andproviding lower and upper fluid accumulating regions within said casing,said lower and upper regions communicating through ports insaid casingwith said lower and upper zones respectively, first reciprocal pumpmeans carried by that portion of said flow tubing depending in saidlower region beneath said well packer, a first inlet in said ow tubingimmediately below said packer, said first pump means having a secondinlet, said first pump means having a first standing valve and a firsttraveling valve for controlling ow through said second inlet, said firsttraveling valve operatively carried by a hollow rod section whichslidably extends through a first fluid seal in said flow tubingpositioned above said first inlet, the interior of said hollow rodsection communicating at one end with said second inlet through saidfirst standing valve and at the other end with the interior region ofsaid fiow tubing above said first fluid seal, an auxiliary flow tubingdepending within said upper region of said casing and communicating at apoint above said first fluid seal with said interior region of said flowtubing, an auxiliary fiow tubing depending within said upper region ofsaid casing and communicating through a cross-over in the said firstinlet through an outlet in said flow tubing positioned below said firstuid seal, the upper end of said auxiliary ow tubing extending to thesurface of said well bore, a solid rod extension connected to andcarrying said hollow rod section which slidably extends through a secondfiuid seal in said flow tubing which defines the upper end of saidinterior region, second reciprocal pump means carried by that portion ofsaid ow tubing above said 9 second fluid seal, said second pump meanshaving a third inlet positioned above said second fluid seal, saidsecond pump means having a second standing valve and a second travelingvalve controlling flow through said third inlet, said standing valveconnected to and carrying said solid rod extension, said secondtraveling valve connected to and carried by a solid sucker `rod whichextends upwardly in said ow tubing, said third inlet communicatingthrough said second traveling and standing valves with a. flow passagein said ow tubing above said second pump means, the upper annulus ofsaid casing functioning as a ow passage for the gas produced from saidupper zone.

References Cited in the tile of this patent UNITED STATES PATENTS2,797,642 Bloudoff July 2, 1957

